linux-kernel - RE: [PATCH v11 12/12] scsi: ufshpb: Make host mode parameters configurable

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Date:   Mon, 21 Jun 2021 06:43:11 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     "daejun7.park@...sung.com" <daejun7.park@...sung.com>,
        "James E . J . Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Bart Van Assche <bvanassche@....org>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        Zang Leigang <zangleigang@...ilicon.com>,
        Avi Shchislowski <Avi.Shchislowski@....com>,
        Bean Huo <beanhuo@...ron.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>
Subject: RE: [PATCH v11 12/12] scsi: ufshpb: Make host mode parameters
 configurable

> Hi Avri,
> 
> >diff --git a/Documentation/ABI/testing/sysfs-driver-ufs
> b/Documentation/ABI/testing/sysfs-driver-ufs
> >index d001f008312b..b10cecb286df 100644
> >--- a/Documentation/ABI/testing/sysfs-driver-ufs
> >+++ b/Documentation/ABI/testing/sysfs-driver-ufs
> >@@ -1449,7 +1449,7 @@ Description:        This entry shows the maximum
> HPB data size for using single HPB
> >
> >                 The file is read only.
> >
> >-What:                /sys/bus/platform/drivers/ufshcd/*/flags/wb_enable
> >+What:                /sys/bus/platform/drivers/ufshcd/*/flags/hpb_enable
> 
> This part seems to be the problem with my patch. I will correct it.
Maybe if just another spin is really required?

> 
> ...
> 
> >diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
> >index ab66919f4065..6f2ded8c63b0 100644
> >--- a/drivers/scsi/ufs/ufshpb.c
> >+++ b/drivers/scsi/ufs/ufshpb.c
> 
> ...
> 
> >@@ -1697,6 +1704,7 @@ static void
> ufshpb_normalization_work_handler(struct work_struct *work)
> >         struct ufshpb_lu *hpb = container_of(work, struct ufshpb_lu,
> >                                              ufshpb_normalization_work);
> >         int rgn_idx;
> >+        u8 factor = hpb->params.normalization_factor;
> >
> >         for (rgn_idx = 0; rgn_idx < hpb->rgns_per_lu; rgn_idx++) {
> >                 struct ufshpb_region *rgn = hpb->rgn_tbl + rgn_idx;
> >@@ -1707,7 +1715,7 @@ static void
> ufshpb_normalization_work_handler(struct work_struct *work)
> >                 for (srgn_idx = 0; srgn_idx < hpb->srgns_per_rgn; srgn_idx++) {
> >                         struct ufshpb_subregion *srgn = rgn->srgn_tbl + srgn_idx;
> >
> >-                        srgn->reads >>= 1;
> >+                        srgn->reads >>= factor;
> >                         rgn->reads += srgn->reads;
> 
> How about changing it to "rgn->read >>=factor" and placing it outside the
> for statement?
I think zeroing rgn->reads before the loop and then rgn->reads += srgn->reads
Making it clear, even as far as doc, that the region reads is the sum over its subregions.

Anyway, this code was introduced in patch 4, so I will fix it there only if you find it really necessary.

Thanks,
Avri